Means for protecting the exhaust valves in internal-combustion engines



March 31, 1953 G.'P|ELSTICK 2,633,117

MEANS FOR PROTECTING THE EXHAUST VALVES IN INTERNAL-COMBUSTION ENGINES Filed May 5, 1949 2 SHEETSSHEET 1 INVENTOR.

. GUSTAV PIELST/CK -ATTOR4VEYS March 31, 5 G. PIELSTICK MEANS F OR PROTECTING THE EXHAUST VALVES N INTERNAL-COMBUSTION ENGINES I Filed May 5 1949 2 SHEETS-SHEET 2 K M M m m w M G H m Iv AT TO'RNE YS Patented Mar. 31, 1953 .MEANS FOR PROTECTING THE EXHAUST VALVES m INTERNAL-COMBUSTION EN- GINES Gustav. Pielstick, Saint-Germajn-en-I Jaye,

France -Application May 5, 1949; Serial No. 91,562 InFrance May'27,:1948

In modern internal-combustion and explosion engines operated at high average pressures, the exhaust gas temperatures frequently exceed 350 Cain twocycle engines and may reach a temperature as high as 600 'C., in supercharged four-cycle engines, even when provided with large-sized cylinders; gsuch temperature increase causes wear in the under exhaust-valve guide. Said wear is 'ehiefly 'due to the combustion r the film of lubricating oil deposit which collects on theunder portion of the-guide as the latter is repeatedly swept, at each open period of. the exhaust valve, by the exhaust gases whose temperature is above the combustion temperature of the oil. The coke-like residue resulting from this combustion produces an erosion. of the guide due to frictional attrition on closure of the valve. This drawback may be averted by protecting the lubricated portion of the valve-shank and its guide from contact with the heated exhaust gases by means of a screen or bafile.

It is an object of the present invention to provide a method and means for protecting exhaust valves of the type described, particularly efficient in character.

With this object in view, the invention provides a method which essentially consists of interposing a thermal screen, preferably in the form ofa bushing, between the valve-shank guide and the path of the exhaust gases.

According to another object or feature of the invention, the said screen or bushing is thermally isolated from the valve-guide.

Another object of the invention is to provide a device for carrying the above-defined method into effect, and which essentially comprises a screen, preferably in the form of a bushing, interposed between the valve-shank guide and the path of the exhaust gases.

In the accompanying drawings, given for purposes of exemplification only,

Fig. 1 is a fragmentary sectional view of an improved valve embodying the invention,

Fig. 2 is a. similar view of an exhaust-valve having its valve-seat directly provided in the cylinder-head, and

Fig. 3 is a cross-section on line IIIIII of Fig. 2.

In the exemplary embodiment of Fig. 1, the exhaust-valye l is seated on a removable valveseat 2. The guide 3 has an upper cylindrical portion 3a removably fitted in the engine head H. This guide has a lower portion 3b of generally inverted frusto-conical form. At :the

6 Claims. (01. 123 -188) junction of the upper and lower portions of the guide there is formed on the upper portion 3a a reduced cylindrical portion 30 providing a downwardly facing shoulder 3d. In the lower end of the guide there is fitted a sleeve 3e through which the stem, for sliding movement, extends. The guide is isolated from the sur rounding space through which the exhaust gases flow, by means of a guard member herein shown as a'frusto-conical bush member 6. The memher 6 is of the same general configuration as the lower portion 3b of the guide and has an upper cup-like cylindrical end So, an intermediate inverted frusto-cylindrical portion 6b and a lower internally cylindrical portion 60. The portion 6a fits closely on the guide portion 30 and bears against the shoulder 3d. The portion 61) is substantially parallel to the lower guide portion 3?) and is spaced therefrom. The bush 6 acts as a screen and creates a cushion of air 1 effective to protect the guide 3.

The frusto-conical bushing member 6 at its lower, smaller-diameter end, is provided with an end-bushing member 8 guidingly surrounding the valve shank 4 and also acting as a further heat-isolating means for protecting the valve against the action of the high-temperature gases.

As shown in Fig. l, the frusto-conical screening member 6 is formed integrally with the valve seat 2, the upper, screening portion of said member being interconnected with the valve seat 2 by means of spacer arms 5 which do not substantially impede the flow of the exhaust gases.

In the embodiment shown in Figs. 2 and 3, the valve I is directly seated against the cylinderhead 9. The bushing or guard member 6 is in this case supported from an intermediate member 8 surrounding the valve-shank 4. The part 8 is secured to the guide 3. As shown in Fig. 3, the part 8 is formed with a circumferential series of spaced apertures It] provided in a radial flange ll thereof.

It will of course be understood that the invention may be embodied in many other ways than those specifically illustrated and described herein, without exceeding the scope thereof as defined by the ensuing claims.

What I claim is:

1. An exhaust valve assembly adapted for use in internal combustion engines, comprising at least one exhaust valve, a shank for said valve, guiding means slidably supporting said shank, a

bushing member below said guiding means and in spaced relation thereto, said bushing extending over a substantial length of said shank which 3 latter is adapted to slide inside thereof, a separate guard member secured to said bushing and to the said guiding means at a place thereof remote from the said. shank providing thereby for a closed insulating air chamber surrounding the lower part of said guiding means and the said shank, screening them from the hot exhaust gases and limiting the heat transmission thereto.

2. An assembly according to claim 1 wherein said guard member has the shape of an upwardly turned cup.

3. An assembly according to claim 1 wherein said guard is of a frustoconical shape.

4. In a valve and seat unit for internal combustion engines, a valve stem guide, a guard member surrounding the lower part of the guide and spaced therefrom to form an air chamber, a valve seat secured to and depending from said guard member, a valve stem slidably fitted in said guide and extending through said guard, said guard being provided with an opening for said stem, a bushing fitted tightly in said opening and fitted closely on said stem, and a valve carried by the stem in cooperative relation to the valve seat.

5. In a valve and seat unit for an internal combustion engine having a head, a valve stem guide having a cylindrical upper portion adapted to fit closely in said head and having a lower portion of general inverted frustoconical form, a guard member surrounding the lower portion of the guide and similar in form thereto, said guard member having its upper end secured to the cylindrical portion of the guide and having an intermediate portion spaced from the lower portion of the guide to provide an air chamber, a valve stem slidably fitted in said guide, said guard having an opening in its lower end through which said stem passes, a valve seat fixed to and dependent from said guard, and a valve carried by said stem in cooperative relation to said seat.

6. An assembly according to claim 1 wherein said valve stem has a water cooled jacket and said guard member is attached to said jacket.

GUSTAV PIELSTICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

